A plug-in electric vehicle (PEV) is a motor vehicle which includes a rechargeable energy storage system (RESS) including a rechargeable energy source such as a battery, a battery pack, a fuel cell, or a high voltage battery (HV battery), where the rechargeable energy source can be charged from an external power source, e.g., a source of electricity external to the PEV. The electrical energy stored in the rechargeable battery pack may be used in a PEV to power one or more electric motors that provide tractive torque to the powertrain of the vehicle, to propel the vehicle. Plug-in electric vehicles (PEV) include all-electric vehicles, battery electric vehicles (BEV), plug-in hybrid vehicles (PHEV), and electric vehicle conversions of hybrid electric vehicles (HEV) and conventional internal combustion engine vehicles.
The RESS typically includes one or more disconnecting switches, which may also be referred to as high voltage (HV) contactors, or contactors, which provide for the connection of the HV battery to one or more of the charger, inverter, DC/DC converter, and auxiliary high voltage loads such as heating and cooling loads, when the PEV is powered, and for the disconnection of the HV battery from the PEV system to isolate the HV battery from the PEV system when the PEV is not powered. The PEV may be powered, for example, when the PEV system is on or when the PEV is plugged in to an external power source for charging. The PEV is not powered, for example, when the PEV system is off and the HV battery is not being charged. When the PEV is powered, the HV contactors are typically energized at a static or nominal power level which may be a maximum power level for the HV contactor, to ensure that the HV contactor remains in a closed state when the HV current draw through the RESS is maximized, for example, under electric vehicle mode high power demand conditions.
Typically, HV contactors have been sized to be continuously powered at a static maximum power level, where the static maximum power level is the power level required to maintain the contactor solenoid in a closed position when blow-off electromagnetic force and Lorentz force is high, e.g., when the maximum HV current level is being drawn through the RESS, to ensure continuous closure of the contactor during the portion of time the HV current drawn approaches or is at the maximum HV current level and the electromagnetic blow-off force and Lorenz force opposing the closing force of the contactor are at their greatest magnitude. Continuously powering the contactor at the static maximum power level generates elevated temperature and heat at the contactor and at the contacts of the contactor while continuously consuming energy to maintain the static power level.